1. Field of the Invention
The invention relates to a coolable blade.
2. Discussion of Background
GB 2 165 315 discloses coolable blades. There, cooling fluid is directed from the trailing-edge region of the blade to the leading-edge region via turns formed by dividing walls and is then expelled via openings in the blade head. In order to adequately cool the trailing-edge region of the blade, air is expelled from the trailing edge of the blade. For production reasons, however, this method cannot be used in the case of trailing edges having small radii. In addition, in order to cool the trailing edge, a large number of film-cooling holes are necessary, which makes the manufacture of the blade very expensive. Furthermore, the expulsion of air at the trailing edge may lead to a reduction in the aerodynamic efficiency of the blade, since a larger trailing-edge radius is required. DE 1 601 627 likewise discloses a cooled blade which has at its trailing-edge region a radially running cooling passage diverging toward the blade tip. The cooling passage is fed with cooling air via a larger inlet opening. In this case, the cross-sectional area of this cooling passage is approximately the same size as that of the main passage in the blade center and even larger than that of the main passage in the region of the blade tip. The heat-transfer rates in the trailing-edge region of the blade are therefore not better than those in the center part of the blade, and adequate cooling of the trailing-edge regions of the blade can no longer be ensured in the case of a blade subjected to high thermal loading.